fix(desktop): survive a CLI probe candidate that throws on spawn (#793)

spawn() can throw synchronously - on Windows it raises UNKNOWN when PATH
resolves af to a non-PE file, e.g. the WSL Linux binary seen through the
interop PATH of a dev launch. The throw happened inside probeCli's promise
executor before any listeners attached, so the promise rejected, Promise.all
in probeAll rejected with it, and app.whenReady's await initializeCli died
before the tray or window were created: the app ran headless with no UI.

Catch the throw and treat that candidate as not responding, matching
probeCli's documented never-rejects contract.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Author: AbirAbbas

desktop/src/main/cli.test.ts

@@ -5,6 +5,7 @@ import {
   compareVersions,
   effectiveMinVersion,
   parseAfVersion,
+  probeCli,
   selectCli
 } from './cli'
 
@@ -157,3 +158,16 @@ describe('cliCandidates', () => {
     expect(sources).toEqual(['managed', 'managed', 'path'])
   })
 })
+
+describe('probeCli', () => {
+  it('resolves responds:false when spawn throws synchronously', async () => {
+    // An empty command makes spawn() throw before any listeners attach —
+    // the same shape as Windows throwing UNKNOWN for a non-PE binary on PATH.
+    // probeCli must swallow it: a rejection here fails the whole probeAll and
+    // the app never creates its tray or window.
+    await expect(probeCli({ command: '', source: 'path' })).resolves.toMatchObject({
+      responds: false,
+      version: null
+    })
+  })
+})

desktop/src/main/cli.ts

@@ -25,7 +25,7 @@
 // No electron imports: the bundled path is injected by main, so probing,
 // selection, and provisioning stay unit-testable.
 
-import { spawn } from 'node:child_process'
+import { spawn, type ChildProcessWithoutNullStreams } from 'node:child_process'
 import { promises as fs } from 'node:fs'
 import { join } from 'node:path'
 import type { AgentActionResult, CliStatus } from '../shared/types'
@@ -139,7 +139,17 @@ export function probeCli(candidate: CliCandidate): Promise<ProbedCandidate> {
       resolve({ ...candidate, responds, version: responds ? parseAfVersion(output) : null })
     }
 
-    const child = spawn(candidate.command, ['version'], { windowsHide: true, env: childEnv() })
+    // spawn() can throw synchronously (e.g. Windows UNKNOWN when the PATH
+    // resolves `af` to a non-PE file such as a WSL Linux binary). Without the
+    // try/catch that rejects this promise, and one bad candidate then fails
+    // the whole probeAll — the app hangs before creating its tray or window.
+    let child: ChildProcessWithoutNullStreams
+    try {
+      child = spawn(candidate.command, ['version'], { windowsHide: true, env: childEnv() })
+    } catch {
+      done(false)
+      return
+    }
     const timer = setTimeout(() => {
       child.kill()
       done(false)